Emergency Medicine

Sudden Right-Sided Weakness and Aphasia in a 68-Year-Old Woman

Presentation

A 68-year-old woman is brought to the ED after her husband witnessed the sudden onset of right-sided weakness and slurred speech 90 minutes ago (last known well 90 minutes ago). Exam reveals right facial droop, right arm and leg weakness, and expressive aphasia, with an NIH Stroke Scale of 12. She takes lisinopril and atorvastatin and has no history of bleeding, recent surgery, or head trauma.

BP 190/115 mmHg, HR 88, RR 16, SpO2 97% on room air, T 37.0°C, fingerstick glucose 112 mg/dL

After addressing airway, breathing, circulation, and obtaining IV access and a fingerstick glucose, what is the single most important immediate diagnostic step?